The Securities and Exchange Commission calls itself the whistle-blower’s advocate. But one participant in the agency’s lauded whistle-blower program isn’t so sure.

He is Michael J. Lutz, an accounting specialist who raised his hand in early 2013 when he was at Radian Group, the giant mortgage insurer. At the time, Radian was still weathering the subprime crisis; it had insured loads of soured mortgages, and Mr. Lutz believed the company was lowballing the amount it might have to pay in claims on the loans.

Mr. Lutz, 31, worked at Radian’s headquarters in Philadelphia verifying that the company’s internal accounting controls were effective. This task is also known as Sarbanes-Oxley testing, named for the Enron-era legislation that bolstered the penalties for accounting fraud.

Radian was required to set aside reserves against potential losses on bad loans, and Mr. Lutz reckoned that his employer was materially understating those amounts. The company was looking to raise capital through a stock offering, and the lower the reserves, the better the company’s earnings would appear.

When Mr. Lutz voiced his concerns to his superiors, he said he was told to stand down.

“I felt like I was on an island,” Mr. Lutz told me in a phone interview. “This big-insurance-company-versus-this-little-guy is a very lonely and difficult situation to be in. But I felt I had no other choice. I was doing my job and doing what was right.”

After an investigation of Mr. Lutz’s allegations, Radian concluded that he was wrong: Its reserves had been appropriate.

But, for the whistle-blower, the damage was done. Indeed, Mr. Lutz said that before he made an issue of the company’s reserves, he had been thriving at Radian. “I wasn’t some bad egg,” he said. “All my performance reviews exceeded expectations.” About a year earlier, Mr. Lutz said he had received a company award for stellar performance.

When he got nowhere on the reserves issue, Mr. Lutz recalled, he emailed Radian’s internal compliance hotline. He knew he was taking a chance: Those complaints went to an executive who was a high-ranking member of the group that decided the company’s reserve amounts.

Soon, he said, he was disinvited from meetings. After Radian investigated his allegations, the company outsourced Mr. Lutz’s job and those of others in his group. Then Radian gave him a choice: He could take a new position auditing the company’s information technology systems, or he could resign and receive approximately $75,000 in severance.

That sounded fine, until he scrutinized the deal. To receive the money from Radian, he had to sign a document stating that he had not filed a complaint against the company with any local, state or federal agencies. Another stipulation: Accepting the severance would bar him from receiving any “monetary damages or any other form of personal relief” in connection with an investigation or proceeding involving the company.

In other words, he could not receive a whistle-blower award.

Because Mr. Lutz and some colleagues had reported their concerns about Radian to the S.E.C., he did not sign the severance agreement. So he accepted the new position the company had offered. He soon found himself essentially reporting to a low-level employee at an outside vendor. When he asked to go back to financial auditing at Radian, a superior told him that he’d never be allowed to conduct those tasks.

He decided to leave Radian. Luckily, he found employment elsewhere in the field.

Still, Mr. Lutz wonders why the S.E.C. has not pursued the whistle-blower complaint he filed against Radian, which outlined its retaliation against him. “A big reason why people don’t report these things is what happened to me in this instance,” Mr. Lutz said. “That’s a big deterrent to people. Every time issues like mine are not enforced, it reinforces the notion that these pieces of legislation are paper tigers and nothing is going to come of it anyway.”

It’s not as if the facts of the retaliation are in doubt. Last fall, the Labor Department sided with Mr. Lutz in an identical matter he had filed against Radian with the Occupational Safety and Health Administration. After examining the material produced by Mr. Lutz and Radian, the Labor Department agreed that the company had punished him for speaking up; it required Radian to pay him $20,000 in damages.

Then there is the matter of the restrictive severance agreement Radian offered. Its terms are similar to those that have drawn fire from the S.E.C. at other companies recently.

In January, for example, BlackRock, the huge asset manager, settled with the S.E.C. for offering exit agreements that prevented former employees from reaping the financial benefits of whistle-blowing. Without admitting or denying the findings, BlackRock paid $340,000 to settle the matter.

The agreement Radian offered to Mr. Lutz was equally problematic, said Stuart Meissner, a lawyer in New York City who represents him. “He didn’t get severance solely because he participated in the S.E.C.’s whistle-blower program,” Mr. Meissner said. “This needs to be addressed.”

The S.E.C. does not confirm or deny the existence of a whistle-blower case or investigation, but I asked Radian about Mr. Lutz’s complaints against the company. It contested much of his account.

Through an outside spokesman, Steve Murray, Radian said it took Mr. Lutz’s concerns very seriously.

“Radian immediately informed the Audit Committee of its board of directors, and within days engaged a highly respected law firm and ‘Big Four’ accounting firm to perform an independent investigation of the matter,” the company said in a statement. That investigation “ultimately concluded what time has borne out, that there were no instances of fraudulent conduct or a material misstatement of Radian’s reserve position.”

Radian also rejects Mr. Lutz’s retaliation claim, saying that it gave him a raise after he voiced his concerns. The company reassigned him, Mr. Murray said, after its audit committee approved a proposal to outsource its Sarbanes-Oxley testing. Interestingly, it gave that business to KPMG, the same auditing firm it had hired to help conduct its investigation into the reserves matter.

The company also said it disagreed with the Labor Department’s findings but had decided against an appeal.

And what about that restrictive severance agreement?

Mr. Murray, the Radian spokesman, said it had recently changed its policy on such agreements and had removed the restriction on monetary recoveries it had required of Mr. Lutz.

The agreement offered to Mr. Lutz was “prepared with the assistance of outside counsel and contained terms and conditions that were customary at that time,” Radian said. The company continues to believe the agreement complied with laws and regulations.

Corporate employees who speak truth to power about internal operations are already putting themselves in harm’s way. When the S.E.C. doesn’t act on a whistle-blower’s claim that others have found valid, it raises questions about its program.

“I don’t understand how one independent third party — the Labor Department — can conclude that there was retaliation,” Mr. Lutz said, “and another one just ignores it.”

Twitter: @gmorgenson

A version of this article appears in print on , on Page BU1 of the New York edition with the headline: A Whistle-Blower Waits to Be Heard. Order Reprints | Today’s Paper | Subscribe